title: Substrate inhibition of nitric oxide synthase in pulmonary artery endothelial cells in culture.
abstract: The effects of arginine on nitric oxide synthase (NOS) activity and NO production were studied in pulmonary artery endothelial cells (PAEC). Incubation of PAEC with 0-100 microM arginine increased NO production, detected as nitrite in the culture medium, in a dose-dependent manner. In contrast, incubation with concentrations of arginine in excess of 100 microM resulted in a reversible dose-dependent inhibition of NO production, even though intracellular arginine content increased in these cells. The NOS enzyme kinetics were studied in a total membrane preparation and in purified NOS protein and revealed that the Km of arginine as a substrate for NOS is 3-5 microM, the Vmax occurred at 100 microM arginine, and substrate inhibition occurred at >100 microM arginine. Oxyhemoglobin, carboxy-PTIO, catalase, SOD, citrulline, hydroxyarginine, and D-arginine did not change NOS kinetics. These results indicate that substrate inhibition of eNOS exists in porcine PAEC in vitro.
authors.affiliation: Department of Medicine, University of Florida College of Medicine, Gainesville 32601, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Su
authors.forename: M
authors.initials: M
authors.lastname: Couch
authors.forename: E R
authors.initials: ER
authors.lastname: Block
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001565:Benzoates / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D002956:Citrulline / Q000378:metabolism; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007700:Kinetics; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010108:Oxyhemoglobins / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects*; D013482:Superoxide Dismutase / Q000494:pharmacology; D013552:Swine
chemical_list: D001565:Benzoates; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D007093:Imidazoles; D010108:Oxyhemoglobins; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D002956:Citrulline; D009569:Nitric Oxide; C068309:N(omega)-hydroxyarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase